Copying machine



March 11, 1952 PARSONS 2,589,204

COPYING MACHINE Filed Nov. 9, 1945 Patented Mar. 11, 1952 COPYING MACHINE Fred A. Parsons, Milwaukee, Wis., assignor to Kearney & Trecker Corporation, West Allis, Wis., a corporation of Wisconsin Application November 9, 1945, Serial No. 627,685

13 Claims. 1

This invention relates to copying machines and particularly, but not exclusively, to machines having hydraulic transmission mechanism for the copying movements.

In some of its aspects the present invention is similar to the invention disclosed in the copending application Serial No. 600,205 filed June 18, 1945, Patent No. 2,493,828, granted January 10, 1950, and some of the features of the present invention are improvements upon the invention disclosed in the copending application Serial No.'

512,112 filed November 29, 1943, Patent No. 2,493,- 827, granted January 10, 1950.

A purpose of the invention is to provide improved copying control mechanism for the transmission mechanism of a copying machine, and particularly where the transmission mechanism is of the hydraulic type.

A further purpose is to provide improved copying control mechanism for the simultaneous control of two motors respectively operative for relative movement of a tool and a work piece in different transverse paths, and especially where the motors are of the hydraulic type.

Pattern controlled copying involves an initial over-run of at least one of the controlled supports whenever there is a change of copying direction, due to lag between the response of the control mechanism to the change of direction and the response of the transmission mechanism to the control mechanism. A further purpose is to provide an improved primary direction correction means, particularly adapted for hydraulically actuated transmissions, in a form which minimizes over-run.

The over-run just mentioned cannot be eliminated entirely, and a further purpose of the inventionis to provide the mentioned primary control mechanism in a form to utilize the unavoidable over-run for various control purposes including the tracer-controlled operation of means for deceleration of the rate of support movements, and including the tracer-controlled operation of means for change of the relative rate of movement of two supports. A further purpose is to provide mechanism for the control results just mentioned in a form particularly adapted for use with hydraulic transmission.

The unavoidable over-run previously mentioned normally operates to effect a series of oscillations or jiggles of the copying tool relative to the work piece, such oscillations being centered by the tracer approximately on the true line of the copying as established by the pattern.

A further purpose is to provide the primary control means previously mentioned in a form which minimizes the amplitude of such oscillations or jiggles in the first instant, and thereafter operates to progressively reduce the amplitude thereof in a manner to effect oscillations of minimum amplitude in minimum time. A further purpose is to provide mechanism for the control results just mentioned in a form particularly adapted for use with hydraulic transmission mechanism.

A further purpose is to provide, in combination with a primary copying control means, a supplemental control means cooperative with the primary control means in a manner to assist in the previously mentioned results thereof, and operative to substantially eliminate oscillations or jiggles during the copying of straight-path pattern portions; and to provide such supplemental control means in a form particularly adapted for use where the transmission mechanism is of the hydraulic type.

A further purpose is generally'to simplify and improve the construction, organization, and operation of copying machines, and particularly for copying machines'having hydraulic transmission mechanism.

Various modifications of the invention herein illustrated and described are contemplated, and it is to be understood that the invention includes all modifications within the spirit and scope of the claims.

Throughout the specification the same reference characters have been used to identify the same parts, and in the drawings:

The single figure is a diagram showing a transmission and control mechanism incorporating the invention. 4

Referring to the drawing, an out-in support I and a line support 2 are both driven from an electric motor 3 of substantially constant speed type, or from other suitable constant speed driver means, the driver 3 actuating a variable-volume positive-delivery pump device 4 which draws liquid from a reservoir 4a and is connected through a reverser valve 6 for actuation of a hydraulic motor la having a piston lb for driving the outin support I in either out or in direction according to the position of reverser 6, the pump being simultaneously connected through a reverser l to a hydraulic motor 2a having a piston 2b for driving the line support 2 in either right or left direction according to the position of reverser I.

The machine of the drawing includes a tracer device I0 and 9. copying tool- [2 which are fixed with support I for bodily movement therewith by the means of suitable brackets, not shown, and also includes a cooperating pattern and work piece which are fixed for bodily movement with support 2 by the means of suitable fixtures, not shown. Suitable power means, not shown, is provided for rotation of the tool I2. For certain types of copying operations, the tool I2 traverses the work by successive opposite directions of line movement which are spaced apart by cross movement in a third path, transverse to both the line and the out-in paths. Transmission and control mechanism for such cross movement is provided for the machine, but being wellknown in various forms, is not here shown.

The tracer I includes a stylus or pattern-contacting member Illa carried on one end of an extended rod or shank IOb having a ball-form pivot portion at Inc carried in a suitable socket provided on the tracer frame or support IIid. At the other end the shank IIlb carries a cone socket engaging a ball Inc which also engages a similar cone socket on the lower end of a plunger III guided in frame Ind. At its upper end the plunger I01 engages a pivoted contactor bar Illg which is continuously urged by a spring I071 in a direction to establish a predetermined position of the stylus I'Ila relative to the frame Iild, downwardly and laterally, the plunger being guided in frame Hid in such manner that the ball I0e operates to center the stylus laterally while the pivot IlJc operates to fix the position of the downward stylus movement.

The tracer contactor bar Iflg carries a yieldable contactor member Illhh, and associated therewith'isan in contact I01 and an out contact Il lk each adjustably carried by the frame IIld. Thain contact IIJi is adjusted to such a position that when stylus Ifla is free of the pattern, whereby it is in the predetermined laterally centered anddownwardly limited position to which it is continuously urged, as aforestated, the in contact is closed for operation of control means, later described-from a power circuit II. The out contact I0k is adjusted to such a position that when the stylus isshifted from the described position occupied when the in contact'is closed, either upwardly or in any lateral direction, the in contact I012 will be opened and the out contact IIIIc will'be closed for other control effects, later described, from the circuit I I.

-It will be understood that for purposes of the present invention various well-known types of tracer devices ID may be used for the mentioned alternative in and out control effects, and the use of any suitable type is contemplated. It is preferable for reasons later apparent, although not necessary, that the stylus Illa should have a control position intermediate between the described in and out positions, as shown in the drawing, in which the connection of the control circuitII isinterrupted. In the tracer I0 such interruption is effected by suitable spacing of the in and out tracer contacts.

The out-in reverser valve 6 includes a shiftable plunger 6a, an inlet port 61) connected to receive pressure liquid from pump 4 through a oneway valve device I4, two ports 60, 6d respectively connected to the in and out direction ports of the motor Ia, and two outlet ports 6e, 6 each connected to return liquid from motor Ia to the reservoir 4a through an out-in back-pressure valve I5. The plunger 6a is shifted to the right from the central position shown in the drawing by a solenoid coil 6g whenever the out tracer contact IIllc is closed, and shifted to the left whenever the in tracer contact Illi is closed. The arrangement of the valve ports is such that when the-valve plunger is in the central position, shown in the drawing, both of the ports leading to motor Ia are closed, but when the plunger is shifted rightwardly, pressure liquid from pump 6 normally urges support I in an out direction, and when the plunger is shifted leftwardly, pressure liquid from pump 6 normally urges support I in an in direction. During copying operations, the operation at times differs somewhat from the normal operation just described, as will be hereinafter explained.

The valve plunger 6a includes tapered grooves suitably arranged relative to the ports for the described connection of pump 4 and motor Ia and, as diagrammatically shown in the drawing, the grooves are of a form and relationship to provide throttle portions such that in either direction of movement of motor Ib and support I the plunger may be positioned to set up a variable resistance to the flow of liquid through the valve, such resistance being negligible when the valve plunger is in either of its extreme in or out direction positions, but increasing as the valve plunger is shifted from the extreme positions. When the plunger is in the central position shown in the drawing, the effect is to prevent either directional movement of support I.

The line reverser valve I includes a shiftable plunger Ia, an inlet port 1b connected to receive pressure liquid from pump 4, two ports 10 and M respectively connected to the left and right direction ports of the motor 2a, and two outlet ports Ie and If each connected to return liquid to the reservoir 4a through a line back-pressure valve [6. The valve plunger la provides grooves, as shown, so arranged that movement of the plunger to the right or left of the central position shown in the drawing eifects a corresponding direction of movement of support 2. The valve plunger la is shiftable by the means of a pivoted lever I8, which, in turn, may be operated either by a manual lever I8a or by the movement of support 2, there being a lever portion I8b projecting into the path of spaced dogs I9a, I9b adjustably fixed on the support 2. The lever I8 and dogs I9a, I9b operate to effect automatic reversal of direction of the line movement after support 2 has traveled a certain distance in either direction as determined by the adjustment ofdogs I9a, I9b. Thus, during movement of support 2 to the right the dog I9a contacts lever I8 and the continued support movement then shifts the valve plunger Ia in the direction for left-hand support movement. Dog Nib similarly but oppositely shifts the lever when the support is moving in left direction. The connection of lever I8 and plunger Ia includes lost motion, as shown, whereby the lever passes its central position in either direction of its movement before the valve plunger is shifted sufiiciently to stop the support movement, and as soon as such central position is passed a detent means of any suitable type, diagrammatically indicated-at 2|, operates to continue the shifting-of the valve plunger to effect the reversal of the support movements as stated.

The out-in back-pressure valve I5 includes a throttle member I5a continuously urged toward the closed position by a spring I5b, there being a spring abutment I50 which is adjustable for varyingthe back pressure effected by the throttle. In either position of the out-in valve 6, the valve I5 operates to set up a back-pressure opposing movement of in-out motor piston Ib, but such in-out back-pressure is normally of small value relative to the pressure of the liquid from pump 4. The line back-pressure valve I6 includes a throttle member Ilia fixed on a plunger Ifib, upon which is also fixed a piston I60 operating in a cylinder Hid. The throttle member is continuously urged toward a closed position by a spring I6e having an adjustable abutment I6), but is simultaneously urged in the other direction by pressure of liquid on piston I60, there being a closed channel Ilig connecting the piston to receive pressure liquid from the channel connecting pump 4 to the reverser valves 6, I.

The line back-pressure valve I6 operates for effecting a resistance force opposing line movement, whereby to urge deceleration of line motor 2a and support 2. The pressure on piston I60 varies directly as the pressure of the liquid from pump 4; and the spring I6e, piston I60 and throttle Ilia collectively have characteristics such that the throttle is fully open, whereby to efiect substantially zero back-pressure on motor 2a, only when the pressure of the liquid from pump 4 rises to a predetermined value. The characteristics of the parts mentioned are also such that at a predetermined smallervalue of the pressure of liquid from pump 4 the throttle IBa is fully closed. The connections of pump 4 to motors Ia, 2a operate as a differential means continuously equalizing the pressure available at the reverser valves 6, 1 for driving the motors I, 2, and said smaller pressure value of the pumped liquid is determined for any given machine according to the capacity rating of the machine, being such that when said smaller pressure is applied through the reverser valve 6 to the in-out motor it is sufficient to accelerate the out-in motor Ia together with support I at valve 6 is in either in or out position the velocity of in or out movement of support I will be accelerated at a rate not less than the above mentioned minimum rate. The acceleration rate will sometimes be greater than said minimum rate as, for example, when there is no instant cutting load opposing the in-out movement. In any event, such acceleration of .the in-out velocity results in a simultaneous corresponding deceleration of the velocity of the line support 2. Thus, the delivery volume of pump 4 being constant,

"any increase of the volume of liquid delivered to the in-out motor la. as occurs during the described acceleration of the in-out velocity, re-

sults in a corresponding decrease of volume delivered to line motor 2a, whereby the backpressure force imposed on line motor 2a by valve 7 I6; and by the instant cutting load opposing sup- :port 2, etc., operates to 'decelerate the line sup- :port ,2 simultaneously :with the, acceleration, of

fthe in-out support I.

i-Thevolumetric displacement of motors I.a,'2a

may be substantially equalzin either directionof 6 motor movement, and substantially the same for both motors. In such case said differential interconnection of the motors establishes a constant value, as determined by the adjustment of pump 4, for the sum of the speeds of supports I and 2. The transmission itself, due to said differential interconnection, is indifferent as to the relative support speeds and, unless prevented as later described by the copying control mechanism, the simultaneous in-'out acceleration, line deceleration, effected by valve I6 as above mentioned results in zero line speed and maximum in or out speed, whereby the movement of the tool is in straight in or straight out direction, as determined by the position of reverser valve '6.

It results from the above described characteristics of the machine that whenever the stylus Illa is free of the pattern, whereby the tracer in contact I02 is closed and valve 6 is shifted to in position there will be movement of support I in the direction until such time as the stylus abuts the pattern whereby to close the tracer out contact;- and whenever such inward movement efiects the closing of the tracer out contact and shifting of valve 6 to the out position there will be outward movement of support I until the stylus again moves free of the pattern, etc. The tracer I0 therefore normally operates to efiect cyclic oscillations or jiggles which are centered by the tracer substantially on the true line of the copying, that is to say on the path which the axis of the stylus would follow if the stylus were maintained in such pattern contact that the in and out tracer contacts are both. open. For certain copying the cycles may include phases of in deceleration, out acceleration, out deceleration, in acceleration, in deceleration etc. which follow one another in the order recited, but in any event the copying will normally include cycles of alternate acceleration and deceleration of the in-out movement.

At the starting point of each of the deceleration phases of the in-out cycles theclosing of one or the other of the tracer contacts operates to shift the plunger 6a of valve 6 to a directionposition opposite to the instant direction of movement of the in-out support I and motor Ia. Thus. if the previous movement was in, the closing of the tracer out contact operates to shift valve 6 to an out position when the tracer stylus strikes the pattern surface as previously described, and if the previous movement was out, the plunger is shifted to its in position. Any such shifting of the valve plunger to a directionposition opposite to the instant support movement operates in either direction of support movement to connect the instant outlet port-of the motor Ia to the inlet port of the valve 6, and the momentum of the various moving parts including support I etc. would then normally operate to force a return flow of liquid-from motor Ia through valve 6 and into the support channel one-way valve acts as a positive brake device substantially instantly arresting the previous direction of movement of support I and motor Ia,

since the energy of momentum oi support I etc.

operates in the first instance to effect a relative very high back-pressure in the closed channel connecting between the piston lb and one-way valve I 4. However, if the previous-direction movement of support I is reduced to zero velocity acsaam by the described positive-brake action of the valve l'4,:such backepressure decreases-to a, point where-the pressure of l-iquidfrom pump 4 operates to start the next succeeding acceleration phase of the oscillationsythatis to say an acceleration of motor Ia and support I in "the direction corresponding to the instantposition of plungertaof valve -6. Similarly, if .the valve is returned to its'previous in or out position .beforezero velocity is effected, as will occur during copyingcertain angles, the "pump -pressure then operates to start the :next acceleration phase.

.It will be seen that-by reason of the described positive-brake action of valve [4 duringthe decelerationphases, any over-run ofthe support I, in

either in or out direction during the described in-out oscillations, iszreduce'd to a minimumvalue. Furthermore, the decelerating force efiected by said positive-brake means is normally :considerably greater than the. acceleration force available from pump '4, whereby deceleration for each halfcycle of the oscillations is effected at a :rate greater :than the acceleration rate for the same half-cycle of the oscillations, andfit results that the in-outioscillations are progressively reduced in amplitude, in a manner fullyexplained' insaid Patent No. 2,493,827 issued January 10, 1950, and

said Patent No. 2,493,828 issued January 10,1950.

'The described tracer-controlled in-out oscillations, being centered substantially on the two line of the copying and limitedas to their amplitude, as described, thereby operate to limit the volume of liquid delivered from pump l to in-out motor la in accordance with the instant pattern angle. Thus if the instant pattern angle is "asmeasured-from a base line'parallel to the-path of the line direction movement, then'the in-out oscillations operate to limit the liquid flow from pumpl tomotor ta to substantially zero-volume, since there is noactual advance in either in or out direction and all liquid from pump 4 is rejected by motor'l-b except a relatively very small volume utilized for the acceleration phases, such volume decreasing as the amplitude of the oscillations is decreased as described. The constant speed driver 3 therefore must "operate to force substantially all the volume of the'liqu-id' from positive delivery pump-4 to *be delivered to ithe motor 2a. Or, if the instantpattern angle*is-45 either inwardly or outwardly asmeasuredfrom a "base line parallel to the line path-of movement,

then the rate of advance of both supports will be equal and the described in-out oscillations operate to force thernotor 2a to accept a-vo'lume of liquid substantially'equa-l to half the'volume delivered by the pump 5. Similarly, for any in stant pattern angle through 0 to '90 either inwardly or outwardly, the describedin-out oscillations operate for driver 3 to force the line motor 2a to accept that proportionate part of liquid from pump 4 which is rejected by the in-out motor by reason of the oscillations bei-ng centered on the true line of the copying.

The first result of the described in-outoscillations is to increase the pressure o'f-the pumped liquid in the channel leading to the linereverser valve 1, since the-excess liquid-has then no outlet except through motor 2a, and correspondingly to increase the pressure applied through channel 169 to the piston I 80 of line back-pressurevalve [6. Such initial increase of the-pressure of the pumped liquid operates todecrease the value'oi the line back-pressure resistance normally established by valve l6, whereby 'tocorrespondingly pressure.

'8 reduce the value of pump pressure required to force the surplus of liquid'to the motor 2a.

Thus, as previously stated, the throttle lGaof valve Hi is closed at a predetermined minimum pressureof the pumped liquid operating onthe piston 16c and opened by an increase of such The operating characteristics of the valve l6 are such that a relatively small increase above said minimum pressure of the pumped liquid operates to materially reduce the backpressure opposing the line movements. It results that, when the in-out oscillations operate as described to increase the pressure of the pumped liquid, the back-pressure normally opposing movement of the line motor is materially reduced with a corresponding reduction of the power whichotherwise'would be required from driver 3 to-force-the liquidrejected by the in-out motor to flow to the line-motor. Where the-linebackpressure is'controlled as'described the maximum .to receive the liquid rejected by the in-out motor being inmost part supplied by the decrease of line back-pressure.

Summarizing the preceding explanation: The described tracercontrolled in-out oscillations or jiggles operate to enforcea rate of advance in in -.or out direction which follows the instant pattern angle irrespective of the instant rate of line movement, and simultaneously operate in the manner described toeriforce a line rate of movement such that the relative rate of advance in an in or out and line direction are correctly proportioned .to suit the instantpattern configuration irrespective of the instant adjustment position of the pump :4. At the same time, the-described positive-brake action of the one-way valve l4 operates during any in-out oscillations to minimize over-run in either'in or out direction, whereby to minimize the amplitude of the initial oscillations and subsequently operates to progressively reduce the amplitude of the oscillations, and during the oscillations the described adjustment of "back-pressure :valve '16 operates to establish a; pressure difierential as required for acceleration of :the .line support without any considerable. increase .in the. pressure of the piunped liquid.

It results from-the described control mechanism that the .in-out oscillations-are automaticallyreduced to substantially :zero amplitude whenever thepattern anglecontinues in the same direction for a sufilcient interval .to .effect the :proper proportioning wofthein, or'out,'.and line speedsin themannerdescribed.

Thus, where the'instant copying continues :at an'angle of 0 for example, .any oscillations which occurred when "the copying angle first changed to 0" will shortly have toperated to accelerate the line movementto substantially the maximum rate determined .by theadjustment of pump 4, as has been explained, and the greatest rate of in-ou-t movement during any oscillations such as then occur-will be onlyslightly greater than zero, since the sum ofthe .in-out and line rates cannot exceed-the maximum rate of movementin either :path. Under such conditions of substantially zero .in-iout :speed the alternate tude of such oscillations as occur during the continued copying of the angle is only slightly greater than is required for alternately closing the in and out tracer contacts.

Similarly when any pattern angle is continued until the relative in or out and line speeds have been proportioned in the manner described to suit the instant pattern angle, the change of rate in the in or out direction required to maintain the oscillations centered on the true line of copying is so small that the oscillations efiect only, negligible departure in either direction from the true line of the copying.

Moreover, during th copying of any straightpath pattern portion as just described, the operation of certain supplemental control mechanism is such as to eliminate the in-out oscillations.

Thus, during the in-out oscillations the valve plunger 6a is alternately shifted in opposite directions, as has been described. In the central position of the plunger, which is the position shown in the drawing, both of the valve ports leading to motor la are closed whereby motor la and support I would be prevented from movement in either direction if the plunger remained in central position. By reason of the tapered throttle portions of the valve plunger 6a, free outlet of liquid from motor la for either out or in direction of movement is efiected only when the valve plunger is fully shifted to corresponding out or in position. When the valve plunger is shifted in the out direction, to the right in the drawing, movement of support I can occur in the out direction, but the tapered throttle portions are arranged in such manner that a suitable positioning of the valve plunger may obviously operate to effect a throttle-brake resistance suflicient to balance any instant force otherwise acting to drive the motor la in an out direction. Similarly as the valve plunger 6a is shifted to the left, in an in direction from the central position, a suitable positioning of the valve plunger may operate to efiect a throttlebrake resistance which balances any instant force otherwise operating to drive the motor la in in direction.

The described throttle-brake action of the plunger 6a operates during the in-out oscillations to anticipate and to supplement the described positive-brake action of the one-way valve l4. Thus, the positive-brake action of the one-way valve normally starts to operate only after the valve plunger So has passed through its central position in one or the other directions of plunger movement, but the throttle portions of the valve plunger start to progressively increase the throttle-brake resistance opposing movement of motor Ia immediately when the valve plunger starts to move from the extreme positions at the beginning of each deceleration phase of the oscillations, the resistance increasing to effect a positive-brake result somewhat before the time when the plunger reaches its central position.

Furthermore, whenever the pattern configuration maintains a straight-path direction for a period sufficient to efiect oscillations of relatively small amplitude, as previously described, a point is reached where neitherof the out and in contacts oftracer in remain closed long enough to effect a complete shifting of the'valve plunger 6a to either of the extreme positions of its movement. The result is alternatively opposite partial movements of the valve plunger, suchpartial movements being centered on the-plungerthe throttle portions of the plunger to balance the instant pressure differential otherwise acting on motor la. For 0 pattern angles, for example, such alternately opposite partial plunger movements are centered on the central position of the plunger. Such partially completed shifting movements of the plunger 6a. operate to increase the average value of the resistance forces opposing movement of motor la during the acceleration phases of the in-out oscillations since the plunger does not then effect either extreme position in which the throttle-brake resistance is zero. It results that the ratio of rate of de-, celeration to rate of acceleration during the oscillation cycles is increased, whereby the previously described progressive reduction of oscillation amplitude is materially assisted, and this in turn operates to still further reduce the alternately opposite movements of plunger 6a. The

final result is that where the pattern configuration continues for a sufficient interval in a straight path, the plunger 6a comes to rest in the position in which its throttle-brake efiect balances the in-out driving force, at a time when both-of. the contacts of tracer III are open. The copying then proceeds without any in-out oscillations in the straight-path direction determined by the pattern until such time as a change of pattern angle, or some other change of copying condition, operates to close the one or the other of the tracer contacts.

It will be seen that the described tracer-controlled throttle-brake result of the valve plunger 6a operates to supplement the primary control effected by the out-in oscillations for the progressive reduction of oscillation amplitude, and for properly proportioning the relative ratio of in-out and line speeds, and for efiecting straight-. path copying of any straight-path pattern portions.v It is to be understood, however, that other methods may be used for progressively adjusting the throttle-brake resistance opposing the in-out motor, and any suitable method is contemplated. Other methods suitable for such result are shown in the Patent No. 2,493,827, issued January 10, 1950, and in Patent No. 2,335,304, issued November 30, 1943.

In the described machine, the transmission mechanism operates without lost motion and substantially rigidly throughout. Thus, the driver 3 at the driving end of the transmission and the valves [5 and I6 at the driven ends of the respec tive in-out and line trains operate to establish and continuously maintain the intermediate train portions under a uni-directional compression strain determined according tothe characteris tics of the line back-pressure valve I6. As previ-. ously described, the valve l6 and its control mechanism are such that the pressure of liquid from pump t varies only through a small range. It results that the copying operation is substantially free from various lags or delays which might otherwise be present due to slack or lost-motion etc., whereby the speed and accuracy of the copy-. ing is correspondingly increased. Moreover, the copying is efiected with relatively small expenditure. of. energy, as compared with various other copying methods. Thus, any deceleration of the in-out support I is effected mainly by the energy of momentum of the decelerated parts, as previously described. Furthermore the deceleration of be diverted to accelerate the in-out movement,

and'the acceleration of the line support 2' is effected mainly by the automatic reduction of the back pressure normally opposing movement thereof, as has been described. It results that the'power expended for a copying-operationin the" present machine is only slightly greater than would be required for removing a corresponding amount of work material in any normal machine tool operation.

The line back-pressure efiect of valve I6 and its control means is determined by the maximum rated capacity of the machine, as has been stated. For'many copying operations, however, a given machine is not required to operate at full rated capacity. For such operations the normal backpressure efiect of valve l6 may be correspondingly reduced, as for example by the adjustment of the spring abutment H) in a direction to reduce the'pressure of spring lGe. Such back-pressure reduction may also be made by means which assist the piston I60 in overcoming the pressure of spring Hie, and an example of suchmeans is diagrammatically shown at 20 in the drawing where a solenoid 20a has a core 201) fixedwith the'valve stem 56b, the solenoid being energized from a source 200 and the value of the effective back pressure being determined to suit the instant copying operation by a manually adjustableresistor device 20d.

What is claimed is:

1. In a hydraulic control system for a machine including an in-out support anda'line support disposed for relative movement to said in-out support, two hydraulic motors for movement of the' different supports respectively, driving means including a power driven pump. and channels connectingsaid pump for simultaneous'actuation of said motors, reverser valve means for the in-out support motor; back pressure valve means adjustable for variably opposing the line-support motor, operating connections for thecontrol of said reverser valve means to efiect repeated cycles of'alternate acceleration and deceleration force on said in-out support motor, and one-way valve means connected in the channel to said reverser valve means and operable during the deceleration force phases of said cycles to apply some of. the energy of momentum of some of the decelerated parts to assist in the deceleration result.

2 In a fluid motor control circuitior a machine including an in-out support and a line'support disposed for relative movement to, said.in-out support, two hydraulicmotors respectively" for movement of the different supports; driving means including a power drivenpump'and channels connecting said pump for simultaneous actuation of said motors, reverser'valve means for. the in-out support motor, back-pressure valve means adjustable for variably opposing the line supportmotor, operating connections'for the control of said reverser valve means to effect repeated cycles of alternate acceleration and deceleration force on said in-out supportmotor. and throttle-valve means connected for operation simultaneously with said: reverser valve means toassist in the iii-out support motor deceleration duringsaid cycles.

31 In a hydraulic motor control system for a' machine including'an in-out'support, a'line'support disposed for relative movement to said in-out support, twomotors respectively for said movement' of the different supports, driver means connected for diiferential actuation of said motors, a. reverser device for the in-out support motor,

a variable resistance device for opposing the movement of'the line support motor; operating connections for the control of said reverser device to effect repeated cycles of alternate acceleration and deceleration force on said in-out support motor and supplemental control means including throttle valve .means associated with saidreverscr device and operable therewith operable. in. response to overrunning of one of said motors to efiect a substantially greater deceleration force than an acceleration force during said cycles.

4: In a" hydraulic control system for a copying machine including an in-out support, a line support disposed for transverse movement relative'to the movement of said in-out support, two hydraulic motors respectively for movement of the difierentsupports, driving means including a power driven pump and channels connecting said pump for simultaneousactuation of said motors, reverservalve means for the in-out support motor,

back-pressure valve means-adjustable for variably opposing the line support motor, operating connections for the-control of said reverser-valve means to effect repeated'cycles of alternate acceleration'and' deceleration force on said 'in-out support motor, and supplemental control means including' valve means operable upon overrunning of said in-out support'motor during said cycles to: effect a materially greater decelerationforce than acceleration force and straight-path control means including throttle valve means associated withsaid reverser valve means and controllably operable to substantially eliminate said cycles duringa predetermined portion of the cycle.

5; Inafi'uid motor control for a machine having elements relatively movable in mutually transverse in-out and line paths, two hydraulic motorsrespectively for said'movements in different ofsaid paths, driving means-including a power driven pumpand channels connecting said pumpfor simultaneous actuation of said motors, back-pressure valve means associated with the line path motor and normally urging decelerati'onthereof I whereby: said driving means normally urges acceleration of the in-out path motor, other valve means in the channel leading to said in-out path motor for variably opposing the movement of said in-out path motor, and operating connections for the control of said other valvemeans to effect repeated cycles of alternate acceleration and deceleration force on said in-out path motor, said other valve means including a one-way valve device operative dur ing the'decelerati'on phases of some of said cycles to' utilize someof'the energy of momentum of the decelerated parts to assist in the deceleration thereof 6. In: a fluid transmission for a machine including an in-outsupport and a line' support movable for relative movement to said in-out support, two hydraulic-motors respectively for movement'of the different supports, a positivedelivery adjustable-volume hydraulic pump, a main channel receiving the volume of liquid delivered from said pump, other channels each connected to receive liquid from said main channel and-respectively connected to deliver liquid to the different motors, an outlet channel for the line' support motor-including back-pressure valve means continuously urging deceleration of the rate'of movement of the line support, an outlet channel for the in-out support motor including valve means adjustable for variably opposing the movement of'said in-out support, operating connections for-the adjustment of the-last mentioned valvemeans to effect repeated cycles of alternate acceleration and deceleration of the rate of movement of said in-out support, and one-way valve means in said channel which is connected for delivery of liquid to said in-out motor and operative to prevent return flow of liquid therethrough during the deceleration phases of said cycles.

'7. In a fluid transmission for a machine including an in-out support and a line support movable for relative movement to said in-out support, two hydraulic motors respectively for movement of the difierent supports, a positive-delivery adjustable-volume hydraulic pump, a main channel receiving the volume of liquid delivered from said pump, other channels each connected to receive liquid from said main channel and respectively connected to deliver liquid to the difierent motors, an outlet channel for the line support motor including back-pressure valve means continuously urging deceleration of the rate of movement of the line support, an outlet channel for the in-out support motor including valve means adjustable for variably opposing the movement of said in-out support, operating connections for the adjustment of the last mentioned valve means to effect repeated cycles of alternate acceleration and deceleration of the rate of movement of said in-out support, a piston device connected for varying the back-pressure effect of said back-pressure valve means in accordance with changes in the pressure of liquid in said main channel, and one-way valve means in said channel connected for delivery of liquid to said inout motor and operative to prevent return flow of liquid therethrough during the deceleration phases of said cycles.

8. In a hydraulic circuit for the-operation of a pattern controlled milling machine, a hydraulic motor operatively connected to effect movement along an in-out path, a second hydraulic motor operatively connected to efiect movement along a line path, a source of fluid pressure operatively connected to supply a substantially constant volume of pressure fluid tosaid two motors, a reverser valve associated with each of said hydraulic motors, a back pressure valve associated with each of said hydraulic motors, a control device responsive to pressure exerted by said source of fluid pressure and operative to control the back pressure valve associated with said line path I hydraulic motor, means to control said reverser valve associated with said in-out path motor thereby to control the fluid pressure exerted by said source and indirectly said line path motor, and a one-way valve associated with said in-out path reverser valve in manner to prevent overrunning of said in-out motor upon reversing operation of said reverser valve, the arrangement being such that operation of said motors is correlated in accordance with therequirements of a pattern controlled milling machine.

9. In a hydraulic power circuit, a constant volume source of fluid pressure, a first hydraulic motor operatively connected to receive pressure fluid from said source, a second hydraulic motor likewise operatively connected to receive pressure fluid from said source, a one-way valveassociated with said first hydraulic motor in manner to prevent reverse flow of pressure fluid from said motor, a valve arranged to control said first hydraulic motor in response to external control requirements, a valve arranged to control the flow of pressure fluid through said second hydraulic motor, and a control device responsive to pressure exerted by said source and operative to control said valve controlling the flow of fluid through said second hydraulic motor, whereby the operation of said two hydraulic motors is correlated for cooperative action in response to said external control requirements.

10. In a hydraulic power system, a source of fluid pressure arranged to deliver pressure fluid at substantially constant volume, a first hydraulic motor connected to receive pressure from said source, a reversing and throttling valve disposed in the connection to said first hydraulic motor and operative to control the rate and direction of' operation of said first motor, means to operate said reversing and throttlirlg valve in response to external control, a one-wa valve likewise disposed in the connection to said first hydraulic motor and operative to prevent reverse flow of fluid in said connection upon reversal of said motor, a second hydraulic motor also con-1 nected to receive pressure from said constant volume source, a rate controlling valve associated with said second motor in manner to control the rate of operation thereof, and a, control device responsive to variations in pressure of said pressure fluid resulting from controlled operation of said first motor and operative to control said rate controlling valve in manner to control the rate of operation of said second motor, whereby operation of said two motors may be correlated for cooperative action in response to external control of said first motor.

11. In a hydraulic circuit for the operation of a pattern controlled milling machine, a hydraulic motor operatively connected to effect movement along an in-out path, a second hydraulic motor operatively connected to effect movement alonga line path, a constant volume source of fluid pressure operatively connected to supply pressure fluid to both said motors, a reverser valve associated with said in-out path hydraulic motor, a rate control valve associated with said line path hydraulic motor, a control device responsive to pressure exerted by said source of fluid pressure and operative to control said rate control valve associated with said line path hydraulic motor, means to control said reverser valve associated with said in-out path motor thereby to control said line path motor indirectly, and a one-way valve associated with said in-out path reverser valve in manner to prevent overrunning of said in-out motor upon reversing operation of said reverser valve, the arrangement being such that operation of said motors is correlated in accordance with the requirements of a pattern controlled milling machine.

12. In a hydraulic control system for a copying machine including an in-out support movable for relative movement in an in-out path and a line support movable for relative movement in a line path transverse to said in-out path; two hydraulic motors respectively for movement of the different supports, a positive-delivery adjustable-volume hydraulic pump, a main channel receiving the volume of liquid delivered from said pump, other channels each connected to receive liquid from said main channel and respectively connected to deliver liquid to the diflerent motors, an outlet channel for the line support motor including back-pressure valve means continuously urging deceleration of the rate of movement of the line support, an outlet channel for the in-out support motor including valve means adjustable for.v variably opposing the movement of said in-out support, operating connections for the adjustment of the last ment-ioned valve means under external control. to effectrepeated cycles of, alternate acceleration and; deceleration of the; rate of movement of said in.-out support, and'one-way valve means in said. channel connected for delivery of liquid to said in-out motor and operative to prevent return flow of liquid therethrough during the deceleration phases of said cycles.

13. In a hydraulic control system for a copying machine including supports relatively movable in mutually transverse in-out and line paths, two hydraulic motors respectively for said movement in difierent of said paths, driving means for said motors including power driven pumpmeans, adjustable valve means for opposing the movement of the line path motor, other adjustable valve means for opposing the movement of the in-out path motor, operatingconneotions for the control of the last mentioned valve means during relative movement of said supports in said line path, operating connections for the control of the first mentioned valve 16 means during said movement to maintain a substantially constant pressure of. the liquid deliveredfrom said pump means, and supplemental means for adjustment of. said first mentioned valve means for variably determining the value of said substantially constant pressure of the liquid.

FRED A. PARSONS,

REFERENCES CITED Thefollowing references are of record inthe file of this patent:

UNITED STATES PATENTS Number Name Date 2,024,256 Sassen Dec. 1'7, 1935 2,059,505 Wright Nov. 3, 1936 2,277,640 Harrington Mar. 24, 1942 2,331,337 Meyer Oct. 12, 1943 2,335,305 Parsons Nov. 30, 1943 2,380,357 Ziebolz July 10, 1945 2,403,519 Gardiner July 9, 1946 

